PARIS — At a museum in eastern France, two men disguised with wigs used a sledgehammer and a hammer to smash a display case and make off with a 2,500-year-old gold necklace. The heist took under four minutes. In a smash-and-grab at another French museum, three masked robbers stole 27 pieces of jewelry valued at more than 4.5 million euros ($5.2 million), busting through two doors to break in. Those thefts took place in July. This week, thieves sliced through a fence and climbed through the window of a museum on the French Riviera and fled with two paintings by Pierre-Auguste Renoir. They abandoned two other artworks by the Impressionist master as they made their escape. The rash of the robberies, coming on the heels of last year's stunning jewel heist in France's most famous and most visited museum, the Louvre, show how the country is both blessed and cursed by its troves of treasure accumulated over centuries of conquest, creativity and having money to spend on art. France's passion for paintings, sculptures, ancient artifacts and other valuables and curios is a source of national pri